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Required and Released Energy

Posted: Sun Jan 10, 2016 9:24 pm
by Catherine Lowe 1B
On page 18 in the course reader, it states that when bonds are broken, energy is required, and when bonds are formed, energy is released. I always thought that when bonds are broken, energy is released, and to form bonds, energy is required. Why is the former true?

Re: Required and Released Energy

Posted: Sun Jan 10, 2016 10:07 pm
by Melissa Ikeda 1K
A bond is formed when the resulting molecule is more stable (lower energy), so therefore if two atoms form a bond, energy is released to reach this lower energy state. Energy is required to break a bond because as stated before, a bond is more stable (lower energy), so to break a bond and return two independent atoms to their higher energy state requires energy--> to go from a low state of energy to a higher state of energy requires you to put in energy.

Re: Required and Released Energy

Posted: Sun Jan 10, 2016 11:39 pm
by sophiadyang1L
I believe it has something to do with how if a bond is broken, it is always endothermic. It is always endothermic because more energy is required to break bonds than the energy needed to form bonds. (Products - reactants will come out to be positive)

Re: Required and Released Energy

Posted: Sun Jan 10, 2016 11:59 pm
by Hannah Markovic 3C
When a bond is broken, the parts of the former molecule are now less stable than they were, especially if radicals are formed. They "do not want" to be less stable, so you need to use energy to force it into that state. On the other hand, atoms are more stable when bonded together, so they will release energy when a bond forms since it takes less energy for them to stay in that state.

It also helps to think of it as similar to potential energy. Breaking a bond is like forcing a ball up a hill - you need to put in energy for it to occupy that state. At the top of the hill, it is less stable and more likely to roll down to a lower elevation (wants to lower its potential energy). If the ball rolls down the hill, like forming the bond, the potential energy is released as kinetic energy and the ball reaches a state where it is more difficult to decrease elevation further and the ball is thus in a more stable state.